Valve function and structure of Detailed Valve (controlvalve) for regulating the medium flow, pressure and liquid level. According to regulate parts of the signal, the automatic control of valve opening, so as to achieve medium flow rate, pressure and level of regulation. Electric Gas Valve sub-control valve, pneumatic control valve and hydraulic control valve.

By the electric control valve actuator or pneumatic actuator and control valve composed of two parts. Regulation and is usually divided into direct and straight-through single-block two-seater two, the latter with flow capacity, small and unbalanced to do the characteristics of stable operation, it is generally suitable for high flow, low pressure drop and leakage occasions.

Cv flow capacity is to select one of the main parameters regulating valve, the flow control valve capacity is defined as: when the control valve fully open, the pressure differential across the valve is 0.1MPa, the fluid density 1g/cm3 per hour flow path the number of flow control valve, called the flow capacity, also known as flow coefficient for Cv, said unit t / h, liquid Cv value calculated.

Flow capacity of Cv value according to the size of look-up table, we can determine the valve nominal diameter DN.

Control valve flow characteristics, pressure differential across the valve is maintained in constant conditions, the medium flows through the valve relative to flow and the relationship between its opening. Control valve flow characteristics are linear features, such as the percentage of properties and characteristics of three kinds of parabola. Note the significance of the amount of three kinds of features are as follows:

(1) the percentage of properties (log)

The relative percentage of properties such as stroke and not a linear relationship between the relative flow rate, each point in the trip itinerary changes caused by unit changes in the flow of traffic to this point is proportional to the percentage change in flow rate is equal. So it has the advantage of flow-hour, small changes in flow, the flow is large, the flow changes, which is in a different opening, and have the same regulation accuracy.

(2) linear characteristic (linear)

Linearity of the relative stroke and relative flow into a linear relationship. Unit change in itinerary changes caused by the flow is constant. Flow, the flow changes in the relative value of small, traffic hours, the flow rate variation in relative Gas Burner Valves.

(3) parabolic characteristic

Flow according to the itinerary change is proportional to the second side, the general linear and equal percentage of intermediate characteristics.

From the analysis of the three features can be seen on its performance in terms of regulation, to the percentage of properties for the optimal adjustment of stability, good regulating performance. The linear parabolic characteristic feature off than the regulation of performance, according to the requirements of different use cases, the selection of any of flow characteristics.